The present invention relates to systems, methods, and devices for imaging and image processing. Although specific reference is made to telestration and tissue tracking with a three-dimensional (3-D) display, embodiments of the present application may be useful in many fields that match images, for example image guided surgery.
The basic goal of image guided surgery (IGS) is to enhance a surgeon's experience and surgical results by providing real time information derived from single or multiple imaging modalities. With IGS, the surgeon uses indirect visualization of tissue to operate. The indirect visualization of tissue can come from many image sources, and IGS can utilize images from sources such as endoscopic, fiber optic, x-ray, computerized tomography (CT), magnetic resonance imaging (MRI), and ultrasound. IGS can be used for surgery, training, and simulation. Two particular benefits of IGS can be improved visualization for easier on-line diagnostics and improved localization for reliable and precise surgery. Many forms of guided surgery can present stereo images of the tissue to the surgeon such that the surgeon can visualize the tissue in 3-D. At least some of the known IGS methods can benefit from the matching of images, and at least some of the known methods for matching images can provide less than ideal results in at least some instances, for example when images have few matching features and at least some of the features are not reliable.
Minimally invasive surgical techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. As a consequence, the average length of a hospital stay for standard surgery may be shortened significantly using minimally invasive surgical techniques. Also, patient recovery times, patient discomfort, surgical side effects, and time away from work may also be reduced with minimally invasive surgery.
A known form of minimally invasive surgery is endoscopy, and a common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient's abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately ½ inch or less) incisions to provide entry ports for laparoscopic instruments.
Laparoscopic surgical instruments generally include a laparoscope or an endoscope (for viewing the surgical field) and working tools. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by an extension tube. As used herein, the term “end effector” means the actual working part of the surgical instrument and can include clamps, graspers, scissors, staplers, image capture lenses, and needle holders, for example.
To perform surgical procedures, the surgeon passes these working tools or instruments through cannula sleeves to an internal surgical site and manipulates them from outside the abdomen. The surgeon views the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy, and the like.
Minimally invasive telesurgical robotic systems are being developed to increase a surgeon's dexterity when working within an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location. In a telesurgery system, the surgeon is often provided with an image of the surgical site at a control console. While viewing a 3-D image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices of the control console. Each of the master input devices controls the motion of a servomechanically operated surgical instrument. During the surgical procedure, the telesurgical system can provide mechanical actuation and control of a variety of surgical instruments or tools having end effectors that perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, dissecting tissue, or the like, in response to manipulation of the master input devices.
In many instances, it can be helpful if the surgeon is able to communicate and even receive instruction from another surgeon. Three-dimensional stereo telestration has been proposed to facilitate surgeon communication and teaching. Work in relation to embodiments of the present invention suggests that known methods and apparatuses for telestration during surgery may be less than ideal. At least some of the known telestration methods rely on image processing for telestration, and in at least some instances the surgical images can present significant challenges due to the complexity of a surgical field. The surgical field can produce sparse images in which at least a portion of the images is sparse in texture, features, or contrast, such that matching of the images can be difficult. For example, a surgical field may contain tissues that are smooth and may have specular reflections, and there may be instruments shining and at different depths. In addition, blood and other medical liquids make image matching a challenging task. In at least some instances the images may comprise few features, and at least some of these features may be unreliable for matching, so that reliable matching of the images can be difficult. Further, tissue can move and surgery occurs in real time such that it would be helpful to provide telestration in real time, and some of the known image matching methods may have at least some delay when images are processed. At least some of the known image matching methods may attempt to match all of the pixels in an entire image, which can result in delay in at least some instances. For example, at least some known image matching methods may generate a disparity map of an entire image, which can be computationally expensive and make real time 3-D telestration difficult in at least some instances. Consequently, at least some of the known methods of telestration may provide less than ideal results.
Accordingly, improved methods and systems providing improved image matching and telestration would be desirable, particularly those which work well in complex surgical fields.